Incineration of sewage screenings and the like



Dc.'14, 1937. w, RAlSCH ET AL 2,102,543 INGINERATION 0F SEWAGE SCREENINGS AND THE LIKE f Filed Feb. 1l, 1936 3 Sheets-Sheet l gewag l.

Dec. 14, 1937. wf RAlscH ET AL 2,102,543

INCINERATION oF sEwAGEscREENINGs AND 'THELIKE Y Filed Feb. 11, v1936 s sheets-*sheet 2 Patented Dec. 14, 1937 UNITED STATES PATENT oFFlcE IN CIN ERATION F SEWAGE SCREENINGS AND THE LIKE tion of New York l Application February 11, 1936, Serial No. 63,290

15 Claims.

This invention relates to incineration and more particularly to the incineration ings and the like.

An important object of the invention is to providey a novel and advantageous method of incineration. Another important object of the invention is to provide novel and advantageous incinerating means.v A further object relates to the reduction of heat losses. It is also an object yof the invention to provide for stoking material in an incinerator without opening the incinerator.

In a preferred kembodiment of the apparatus, the screenings or the like are introduced through a gas lock in the roof of the incinerator and fall on a drying hearth, which may be formed of slabs of refractory material supported on transverse members preferably in the form of water cooled metal pipes. At one end of thedrying hearth is a water cooled drying grate and the material isr fed by rotary water cooled stoking devices along the drying hearth and the drying grate. From the drying grate the material drops to the upperreach of a traveling burning grate which carries ofthe traveling grate and be carried away to another pit.

During the movement of the material by the upper reach of the traveling grate, the material may be partially held back and stirred up by suitable means such as rotary water cooled stirrers or stokers turning in a direction to act rearwardly adjacent to the traveling grate and then to lift and move material forwardly in the direction of movement of the upper reach ofthe traveling grate.

'Ihe incinerator may be supplied at one end with an elevated steam drum extending across the incinerator and provided at each Yside Yof the incinerator with downwardly extending pipes or mains supplying water to pipes extending along the lower parts of the sides of the incinerator 45 and communicating with the ends of the rotary right pipes or mains carrying the water upwardly. Each of these upward flow mains is connected with a return pipe or main extending in a gen- 55 Y ports for the drying grate, and then turning upof sewage screenstirrers or mixers adjacent to the top of thek travelingv grate and then with substantially up-v erally horizontal direction toward the steam drum through the upper reach of the traveling grate, v

ypassing upwardly around the end of the drying grate, over the drying grate and hearth, downwardly from the end of the hearth toward a dust pit, and through one'or more combustion chambers to a stack or otherv outletrdevlce. Y

In the burning of the dried material a great amount of heat is generated and this may be used to assist in dryingV fresh material and burning the same. Use may also be made of auxiliary fuel preferably oil or gas in suitable burners provided at suitable points.

Important advantages of the invention reside in the feature of continuous .operation without exposing the material to the atmosphereduring its drying and burning, continuous feed of material, and thorough agitation and mixing of the material during the drying and burning of the screenings.

Other objects, features and advantages will appear upon consideration of the following description and of the drawings, in which Fig. lis a viewvin side elevation of apparatus embodying a preferred form of the invention;

Fig. 2 is a section on the line 2--2 of Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a section on the line 4-4 of Fig. 3; and

Fig. 5 is a section on the line 5 5 of Fig. 1.

In the drawings there is illustrated a furnace having a front wall I0, side walls II, a rear wall I2 and a top I3, all of which are preferably of refractory material which may be re brick or any other suitable material. The top I3 may comprise a plurality of slabs of refractory material suspended from metal beams I4 extending across the furnace and supported by the side walls and a covering I5, preferably of steel plates, above the' beams I4. 'The foundation of the furnace wherev notfexposed to the action of the burning gases may be of any suitable material such as concrete. Heat insulating material may be provided at the outer surface of the front wall I0 and the'side walls II.

The screenings or like material may be introduced or charged into the furnace by means of a hopper I6 extending through the roof or top I3 and provided with a gas Seal or lock. Said gas the lower gate may be turned to dump its load into the furnace where it will fall upon a drying hearth I9.

`The drying hearth I8 extends rearwardly to the top of a bridge wall of refractory material and forwardly to the rear edge of a drying grateY 2|. Preferably the drying hearth is formed of slabs of refractory material bridging the spaces between hollow water-cooled supports or pipes 22, except at the rear edge where the bridge wall I9 is utilized as a support. At the forward edge of the hearth support for the refractory material may be provided by a header 23 constituting the rear edge of the drying grate 20. At the forward edge of the grate 29 is another header 24 and these headers are connected by a plurality of tubes or pipes 25 constituting water-cooled grate bars.

The material on the hearth I9 and grate 2I may be stirred and stoked toward the front wall I0 byany suitable means such as a plurality of water-cooled rotary stoking devices 26 turning in the direction of the arrows in Fig. 3. As illustrated each of the devices is formed of a single pipe or tube bent back and forth alternately into a at grid, the shaft portions 21 of the pipe at the ends of the grid being in alignment and passing outwardly through sleeves 28 fixed in the side walls. At the outer ends of sleeves 2B are bearings 29 in which the shafts 21 turn. At one side of the furnace, on each shaft 21, just outside the corresponding bearing 29, is a worm gear 30 meshing with a worm 3I mounted on a shaft 32 extending along the side of the furnace. Each worm gear 30 and the corresponding worm 3| are mounted in a casing 33 through the outer Wall of vwhich the hollowshaft 32 extends. The shaft 32 on which the worms 3| are mounted may be driven in any suitable manner but asillustrated is driven by an electric motor 34, acting through a speed reducer 35, a shaft 36, and a worm and worm gear connection comprising a worm gear 31 on the shaftY 32. It should be noted that the stoking devices 26 are located rather close together and that interference between successive devices is avoided by arranging such successive devices so that they will be 90 degrees apart.

Material deposited onthe drying hearth I9 will be moved along the hearth and the drying grate 2I until it passes over the header 24 and falls down to the upper reach of a traveling grate 38 which, as indicated by an arrow on Fig. 3, carries the dried material rearwardly beneath the drying grate 2I and the drying hearth I9 and nally discharges the ashes on an inclined grating 39 at the top of an ash-pit 40. The traveling grate 38 may be in the form of an endless belt formed of alternate transverse rows of long links 4I and short links 42 Ypivotally connected together (see Figs. 3 and 4), and may be supported by a rear- ;ward rotatable member 43 and a' forward rotat-,

able driving member 44 having teethy 45 making a riving connection with the traveling grate. The driving member '44 is carried by a shaft 46 on which isV mounted a sprocket wheel 41 and the sprocket wheel 41 is driven by a sprocket chain 48 passing around a sprocket wheel 49 actuated by a motor drive housed in a casing 59.

The upper reach of the endless traveling grate 38 may be supported by transverse metal beams 5I and the lower reach may rest upon longitudinal metal beams 52 supported by transverse beams 53 in the concrete of the foundation, the spaces between the longitudinal beams 53 being filled with suitable heat resisting material, such as packed sand, resting on the concrete base and supported at its rear endV by a at inverted channel 54 forming an extension of the grating 39 and at its front end by a flat inverted channel 55. Any ne material dropping through the upper reach of the traveling grate 38 to the lower reach of the grate will be carried to front of the furnace and dropped into a pit 55 beneath the grate supporting and driving member 44. At this location the forward end of the traveling grate projects through an opening in the front wall IIJ and access of air through this opening is prevented by suitable means such as a steel plate casing 51 enclosing the space above the pit 54.

Above the upper reach of the traveling grate 38 are rotatable stoking devices 58 similar in general to stoking devices 25 but with relatively narrow flat portions to enable them to be located close to the traveling grate 38 and provide adequate free space, beneath the drying grate ZI and drying hearth I9, for the effective use of burners 59 located at opposite sides of the chamber. The stoking devices 58 have at their ends shaft portions 69 extending through sleeves 28 in the side walls I I and bearings 29 at the outer ends of said sleeves. The stoking devices 58 may be driven in any suitable manner, for example from the shaft 32 which drives the upper set of stoking devices. To this end use may be made of bevel gears 6I, mounted on and revolving with the shaft 32, and meshing with bevel gears 62 on upright shafts 63. As illustrated in Fig. l, two of these shafts 63 act directly through worm and worm gear connections on shafts 56 at the ends of stoking devices 58, the worm and worm gear connections being enclosed in casings64, and the other shaft 63 acts on a corresponding worm and worm -gear connection through two intermeshing gears 65 and 66. In all instances, however, the arrangement is such that all of the stoking devices 56 rotate in a clock-wise direction as viewed in Fig. 3.

Air for combustion purposes may be supplied through a duct 51 in the lower part of one of the side walls II and communicating through suitable openings 68 with the space between the upper and lower reaches of the endless traveling grate 38. Passage of air to the portions of grate near the rotatable supports 43 and 44 is undesirable and may be restrained by members or shields 69 suspended from pivots 19 adjacent certain transverse beams 5I supporting the upper reach' of the traveling grate 38. Preferably the shieldsi 69 comprise vertical portions extending downwardly almost to the lower reach of the traveling grate and horizontal portions normally resting ron said lower reach of the grate, the free edgesV of the horizontal portions and the connection between the horizontal portions and the vertical portions being inclined upwardly to permit material on the lower reach to pass beneath these shields. The passage of the air upwardly through the upper reach of the belt may be controlled by deectors or shields 1I positioned at the openings or spaces between the transverse beams 5i. As

.with a damper 1|a.

The air passes upwardly through the upper reach of the traveling grate 38 and aids the burning of theV material on the grate 38 below the burners 59. The gases and products of combustion pass to and upwardly around the free edge of the drying grate 2|, and rearwardly over the drying grate 2| and the hearth I9 to the rear wall I2 where it is subjected to the action of a burner 12 to complete as far as possible the burning of combustible material remaining in the combustion gases. The gases are turned downwardly by the wall 12, thus enabling dust to be deposited in a Vpit 13', and pass rearwardly above a bridge wa1l'14 and through an opening 15 into a chamber 16 and iinallyinto a suitable stack (not shown) or other outlet to the open air. Access to the interiorfof the furnace may bey obtained Athrough a front wall opening 11, normally closed by a door 18, and through sidewall openings 18 and 19.

The preferred form of water-cooling and steam-generating system includes aY combined water and steam drum 80 supported, by means including straps 8|, substantially at the top of the front wall I0. The drum extends transversely of the furnace and near each of its ends pipes B2 extend downwardly from the bottom of the drum. These pipes 82 are connected with horizontally extending pipes or headers 83 connected with the outer ends of the hollow shaft portions 88 of the stoking devices 58v associated with the traveling grate 38. From the connection between each pipe 82 and header 83, there extends downwardly a pipe 84 which may be used for draining the systemand is normally closed by a valve 85. As illustrated the connection between the p-ipes 82, 83 and 84 is a four-way con'- nection 86 of which the unused end may be closed by a plate 81.

At their rear ends, the headers 83 are connected with intermediate, horizontally extending headers 88 connected with the drum 80 by upwardly extending connections or parts 89, and with upper horizontally extending headers 90 connected at their forward ends with the pipes or connections 89. The intermediate headers are connected with opposite ends of the hearth-supporting pipes 22, 23 and 24, andthe upper headers 90 are connected with the hollow shafts 21 at opposite ends oi the stoking devices 26.

For cleaning purposes, the headers are provided at their outer sides with openings in alignment with the openings in the ends of the hollow members extending across the incinerator at its interior, said openings at the outer sides of the headers being normally closed as by rscrew plugs 9|. Of course where rotating parts are connected with the headers, it is desirable to use packing glands 92. In most cases it is desirable to use T-iittings 93. The fitting 94 atv its rearl end of the upper header (Fig. 1) is, however, a four way fitting for connection with the lower header and to provide a cleaning opening in alignment with the upper header. The lower header is preferably provided at its rear end with a three-way connection 95 of which one end may be opened for cleaning. The intermediate header is provided at its rear end with a tting 96 having. a branch for connection with a hearthsupportingV pipe 22, a branch for connection with the lower header, a branch for connection with the upper header, a branch for connection with the intermediate header and a branch on the opposite side of the fitting but in alignment with the middle header for cleaning purposes.

In operation, material such as sewage screenings is introduced into the incinerator, by placing it on the upper gate I1, turning the upper gate to dump its load on the lower gate, closing the upper gate, opening the lower gate, closing the lower gate, and repeating this series of operations when desired. Obviously the gates |1 might be rotated tor make the feed substantially continuous. The screenings may fall on the hearth i9 through the set of rotating stoking devices 26 and then be shifted gradually by these stoking devices along the hearth |9, and. along the drying grate to and over the front edge thereof to fall on the rearwardly-moving upper reach of the endless grate 38. During the rearward movement of the material on the upper reach of this grate, the material will be agitatedand mixed by the stoking devices 58 which tend to resist such rearward movement. The ashes resulting from combustion on this grate will be discharged from the rear of this grate to fall upon the open grating 39 through which they may pass into the ash pit I0 unless prevented by the ap 1|a.` Some of the ine ashes may pass through the upper reach of the grate to the lower reach and be carried forwardly andV dumped into the pit 56.

During this operation air supplied from the duct S1 will pass through openings 38 into the space between the upper and lower reaches of the grate and upwardly past the regulating members or defiectors 1| and through the upper reach and the material thereon to assist the burners 59 in burning the material. The greater part of the combustion gases will then iiow upwardly around the forward end of the drying grate 2| and then rearwardly over this grate'and the hearth I9, thereby serving to dry the freshly deposited material. 'I'he gases will then be subjected to the action of the burner 12 and turned downwardly to remove the dust before the gases pass out of the chamber.

It should be understood that various changes may be made in the construction and arrangement and that certain features may be used without others without departing from the true spirit and scope of the invention.

Having thus described our invention, we claim:

1. `An incinerator comprising a furnace chamber, a drying hearth therein, a grate forming an extension of the hearth, stoking means operaable from the outside of the incinerator without opening the same for moving matter deposited on the hearth in one direction along the same. to the grate and along the grate to fall off the free edge thereof, and means, including a grate at a lower level, to support the dried material for burning and to move the burning Vmaterial in the opposite direction beneath said grate and hearth.

2. An incinerator comprising a furnace chamber, means in the uppery part of the chamber to introduce material without opening the chamber to the outside air, a drying hearth to receive the material thus introduced, a drying grate constituting an extension of the drying hearth, means for stoking the material along the drying hearth stoking devices rotatably mounted in the walls of the chamber and operable from the outside of the chamber, and means, including a i'lre grate receiving dried material from the drying grate,

5 for burning the dried material and discharging the ashes at a desired point.

3. An incinerator comprising a furnace chamber, means in the upper part of the chamber to introduce into the same, without opening the chamber, material to be burned, a drying hearth to receive the material thus introduced, a drying grate constituting an extension of the drying hearth, means for stoking the material along the drying hearth and then along the drying grate until it falls off the free end thereof, such stoking means including a plurality of devices each rotatably supported by aligned shafts forming parts thereof and extending through opposite sides of the chamber, means at the outside of said chamber for rotating said devices, and means at a lower level to support the dried material for burning and transport the material in the opposite direction beneath the drying grate and hearth.

4. An incinerator comprising a furnace chamber having side walls, ends and a top, means for introducing material' through the top near one end without opening the chamber to the outside, a drying hearth to receive said material, a drying grate forming an extension of said hearth toward the otherl end of the chamber, means for stoking said material substantially continuously along said drying hearth and grate and off the free end of the drying grate, and a traveling fire grate to receive material dropped from the edge of the drying grate and carry it in the opposite direction beneath said drying grate and drying hearth to a discharge point.

5. An incinerator comprising a furnace chamber having side walls, ends and a top, means for introducing material through the top near one end without opening the chamber to the outside air, a drying hearth to receive said material, a drying grate forming an extension of said hearth toward the other end of the chamber, means for stoking said material substantially continuously along said drying hearth and drying grate until it drops off the free edge of the latter, a traveling fire grate to carry the dried material falling from the drying i grate back beneath the drying grate and hearth, and means for stirring up the layer of material as it is carried along by the traveling grate.

6. An incinerator comprising a furnace chamber having side walls, ends and a top, means for introducing material through the top near one end without opening the chamber to the outside air, a drying hearth to receive saidmaterial, a drying grate forming an extension of said hearth toward the other end of the chamber, means for 601 stoking said material substantially continuously along said drying hearth and drying grate until it drops off the free edge of the latter, a traveling re grate to carry the dried material falling from the drying grate back beneath the drying grateV 65 and hearth, and means for stirring up the layer of material as it is carried along by the traveling grate, such means including a device revolved about a horizontal axis in a direction to move the material back along the traveling grate and lift 70` it therefrom.

'7. An incinerator comprising a furnace chamber having side walls, ends and a top, means for introducing material through the top of the chamber without opening the same to the outside 75= air,fa drying support receiving said material upon such introduction, said support extending toward one end of the chamber but having a free edge spaced therefrom, stoking means operable from the outside of the incinerator without opening the same for moving material on said support to its free edge, and an endless fire grate having an upper reach receiving material from the free edge of said support and carrying it to a discharge point and a lower reach moving in the opposite direction iine material passed through said upper reach.

8. An incinerator comprising a furnace chamber having side walls, ends and a top, means for introducing material through the top of the chamber without opening the same to the outside air, a drying support receiving said material upon such introduction, said support extending toward one end of the chamber but having a free edge spaced therefrom, stoking means operable from the outside of the incinerator without opening the same for moving material on said support to itsV free edge, an endless re grate having an upper reach receiving material from the free edge of said support and carrying it to a discharge point and a lower reach moving in the opposite direction ne material passed through said upper reach, and means for supplying air from the side between the upper and lower reaches of the traveli-ng grate to aid burning on the upper reach of said endless fire grate.

9. An incinerator comprising a furnace chamber having sidewalls, ends and a top, means for introducing material through the top of the chamber without opening the same to the outside air, a drying support receiving said material upon such introduction, said support extending toward one end of the chamber but having a free edge spaced therefrom, stoking means operable from the outside of the incinerator without opening the same for moving material on said support to its free edge, an endless fire grate having an upper reach receiving material' from the free edge of said support and carrying it to a discharge point and a lower reach moving in the opposite direction fine material passed through said upper reach, means for supplying air from the side between the upper and lower reaches of said endless grate, and means for loosening the material on said upper reach to enable the air to pass upwardly therethrough.

i0. An incinerator comprising a furnace chamber having side walls, ends and a top, means for introducing material through the top of the chamber Without opening the same to the outside air, a drying support receiving said material upon such introduction, said support extending toward one end of the chamber but having a free edge spaced therefrom, means for moving material on said support to its free edge, an endless fire grate having an upper reach receiving material from the free edge of said support and carrying it to a discharge point and a lower reach moving in the opposite direction fine material passed through said upper reach, means for supplying air from the side between the upper and lower reaches of said endless grate, and means for controlling the flow of such air kto different parts of said upper reach.

il. in apparatus of the class described, a furnace chamber having side walls and each, a generally horizontal drying support extending toward one end of Vsaid chamber but having a free edge spaced from such end of the chamber, a plurali-tyr of rotatable stoking devices to move material along said drying support to said free edge,

saidstoking devices being hollow and supported by hollow shafts projecting through said side lower stoking devices and return headers conforming parts thereofr and passing through said side walls, an endless traveling grate at a lower level than said support to receive material moved past said free edge, hollow rotatable stoking devices above the upper reach of said endless grate and comprising at opposite ends hollow shafts passing through the side walls, and a steam and water circulating system comprising outside lower supply headers at opposite sides of the furnace chamber connected with the hollow shafts at the ends of the lower stoking devices, outside return headers at opposite sides of the furnace chamber connected with the supporting pipes of the drying support, and outside return headers at opposite sides of the furnace chamber connected withthe hollow shafts at the opposite Y ends of the upper set of 'stoking devices.

13. An incinerator comprising a furnace chamber having at one end va bridge wallover which the gases of combustion are discharged, a ,dry-

ing hearth extending from the top of the bridge,v wall toward the other vend. of the chamber, a`

drying grate constituting an extension of the hearth and having a free edge spaced from said otherwalL'automatic means for stoking material deposited on said hearth along the same and the grate and over said free edge, a fire grate on which the dried material falls and automatic means for moving the material on the fire grate in a direction opposite to that on the drying Y hearth and grate, and means for supplying air beneath the material on said fire grate, the gases of combustion passing in one direction beneath the drying hearth and grate and back over the top thereof and over the bridge wall.

14. An incinerator comprising a furnace chamber, means in the upper part of said chamber to introduce material without opening the chamber to the outside air, substantially horizontal dryingV support to receive the material thus introduced, means for stoking the material ber and rotatably mounted in the walls of the d chamber so as to be operable from the outside thereof, and means, including a fire grate receiving material from the drying support, for burning the dried material and discharging the ash.

15. An incinerator comprising a furnace chamber, means in the upper part of said chamber to introduce material without opening the chamber to the outside air, a substantially horizontal drying support to receive the material thus introduced, means for stoking the material along the drying support until it falls off one end thereof, said stoking means including a plurality of stoking devicesV extending acrossv said chamber and rotatably mounted in the walls of the chamber so as to be operable from the outside thereof, and means, including a fire grate receiving material from the drying support, for burning the dried material and discharging the ash, said stoking devices including parts extending radially from their axes of rotation and being driven so that radially extending parts of one stoking device may extend between radially extending parts of a stoking device at either side thereof during rotation of the devices.

WILLIAM RAISCI-I. JOSEPH C. WOODMAN. JOHN R. BUFFINGTON. JOHN E. MORRIS. 

